I am trying to figure out what is the best route to take and am trying to figure out if my tune will be affected or if I will need to re-tune. My fuel pump took a dump, I was thinking of just replacing with the same stock pump but then I figured if I have it opened up I might as well go to a Focus SVT pump. All the looking around and tracking down part numbers I came to the conclusion that it is hard to really know if what I am buying is really an SVT Focus pump or something re-manufactured using the core of an SVT Focus pump. My car is N/A with minimal mods and tuned getting 330hp/334tq and I don't see any major mods on the horizon. I am thinking about getting the Aeromotive 325 Stealth to put into the car to get her up and running again. What I am trying to figure out here is if I upgrade to the 325 pump will I need a re-tune to keep from running rich? Is anything in the tune related to the size of the pump or will the pump just do what it has to do to supply my fuel rail with the pressure that it needs based on the adjustments made during the tune?

If I am going to need a re-tune I am just going to go back to the stock pump as there is noone in my area that does tunes anymore that I know of. I have been searching and some people say I will need a re-tune with a bigger pump, some say I won't. I just need a definitive answer so I can get the pump and get my Mach up and running again.

I've been reading up on the 255 and I'm not sure it's made for returnless.

I'm thinking about just going with the Focus SVT pump, I can get that for right at $200 but a Motorcraft stock pump will run me a little over $400. If I could find the stock pump at a reasonable cost I would just do that and call it a day.

So yeller, your saying I may run rich for a while till the computer learns the new pump?

I've been reading up on the 255 and I'm not sure it's made for returnless.

I'm thinking about just going with the Focus SVT pump, I can get that for right at $200 but a Motorcraft stock pump will run me a little over $400. If I could find the stock pump at a reasonable cost I would just do that and call it a day.

So yeller, your saying I may run rich for a while till the computer learns the new pump?

I doubt it'll be that far off. If you went with a 340 I'd say you might need adjustment in your tune.

Quote:

Originally Posted by DSG2003Mach1

Doesn't the focus pumpnrequire some wiring upgrades as well?

I knew guys that dropped them in with no issues. Maybe it's different if you run two. I ran twin GT pumps on a stock FPDM with just a wire upgrade.

when looking for aftermarket pumps, just make sure they support PWM, Pulse Width Modulation, that is what is needed for a returnless system. Way back in the day, when I put a 340lph pump in, I had to have the tune adjusted.

when looking for aftermarket pumps, just make sure they support PWM, Pulse Width Modulation, that is what is needed for a returnless system. Way back in the day, when I put a 340lph pump in, I had to have the tune adjusted.

I would imaging the SVT Focus pump supports PWM, are you saying you only need to adjust time if the pump DOES NOT support PWM??

I would imaging the SVT Focus pump supports PWM, are you saying you only need to adjust time if the pump DOES NOT support PWM??

No. If the pump doesn't support PWM it'll burn up. That's why I was asking if the Walbro 255 is compatible now. Way back when I first started playing with mod motors most companies still included the 255 in their blower kit. But the 255 would burn up because it's designed to work at 100% all the time.

FWIW I went from a stock single pump to twin Cobra pumps in my 01. I didn't adjust the tune and didn't have an issue. So I would think the Focus pump would be ok.

I would imaging the SVT Focus pump supports PWM, are you saying you only need to adjust time if the pump DOES NOT support PWM??

The Focus pump supports PWM. and no, that is not what I am saying, your tune may need to be adjusted after a swap, just ask your tuner. I just remembered that when I put the 340lph in, I also had a boot-a-pump for the factory pump, I had to readjust everything because with both there was not enough adjustment range. I am sure a focus pump is fine.

BTW, I agree, the old 255s did not support PWM and I had a buddy go through three before we figured out why. Then it was painfully obvious.

I did a big write-up on this a few years ago here, I will see if I can find it.

The problem here is finding someone that can tune it. The bigger problem would be if I did find someone who said they could, would I even trust them lol.

I don't drive the car much, I think it had just hit 39k right before the pump died. I'm just trying to get her back up and running again right now. I know I trust a genuine Ford part vs something not designed for the system, or a $40 pump from AutoZone. It seems like the SVT Focus pump is the safest bet at the moment as far as parts go without paying 2x's the money for the stock pump.

I guess the only thing to do is put it in and see what happens, what's the worst running rich could do to it until I can find someone I trust to re-tune it.

If you have an ODBII logger (iPhone works) you can log the fuel pressure and duty cycle. If the duty cycle % freely goes up and down with different fuel usage like WOT vs idling then you will be fine. If during this test the fuel pressure stays within range then you are also ok. You simply want the PCM to have a control range without building to much pressure or not having enough pressure. Ok, so it basically will boil down to making sure fuel pressure stays within the proper range.

Try the Walbro TU229HP it is rated to operate at 13.5 volts and has a flow of 290 liters per hour @ 43 psi. I was running a stock pump with a BAP and had hesitation between the 1 2 shift. Dropped this pump in the hesitation is gone and the car has been running fine.

In all honesty I would be just fine with a stock pump right now. I only have minor mods and based on the last time the car was tuned I was not having any fuel issues. The SVT Focus pump is overkill for me right now but for half the cost of a stock pump I might as well just do that to get the extra flow capabilities if I need it later and to save some $$ now. We have had the car since new in 03 and in the 13 or so years I've had it I haven't even hit 40k miles yet. With 3 little ones and the limited time I am left with between work and family I don't see any significant mods in the near future. I just want to get it back up and running so that I can take it out on the weekends from time to time. That said if anyone knows where to find a stock Ford pump for less than $200 please let me know.

I picked this up right off of Amazon when mine died, Focus SVT pump. Pulled the pump itself out of the housing, dropped right into the mach housing, and away I went with no tuning. Car was running fine when I got rid of it.

I picked this up right off of Amazon when mine died, Focus SVT pump. Pulled the pump itself out of the housing, dropped right into the mach housing, and away I went with no tuning. Car was running fine when I got rid of it.

Ok, so pump came in and I went ahead and ordered a new gasket for where the filler neck goes in.

I am a little perplexed on the pump though. The outside 9f the box has a Ford Motorcraft sticker on it. P/N 3S4Z-9H307-BC which from everything I can find is the Focus SVT part number. The box was stapled shut with those big packaging staples that you have to rip apart. When I took the item out of the box everything looked in order and the pump has a green top. On the top of the basket, the part that would be outside of the tank, there is another sticker that is showing P/N 3S4U-9H307-BB. Not the same number on the box. It has a U instead of a Z and BB in lieu of BC.

Anyone know if the part numbers possibly updated or did I get hit with a bait and switch here??